Atkinson-Cycle 1.5-Liter 4-Cylinder Engine

What’s the Benefit?
Honda engineers update an established engine design with leading-edge technology to create an extremely fuel-efficient powerplant.

The Feature:
The Insight’s engine makes for excellent efficiency as well as responsive power output.

• Developed many decades ago, the original Atkinson-cycle engine improved fuel efficiency by reducing the volume of air and fuel introduced on the intake stroke and compressed on the compression stroke.
• This smaller intake charge would then burn more efficiently during ignition, while still providing adequate torque on the power stroke.
• For the Insight, Honda engineers used the flexibility of the VTEC^® system to simulate the original Atkinson-cycle principles, with operating efficiency that goes far beyond a traditional internal-combustion engine.
• Specifically, one of the VTEC cams delays the closing of its assigned intake valve until much later than usual on the compression stroke.
• The resulting smaller volume of air/fuel mixture then burns more completely and efficiently during the power stroke.
• However, the other intake cam is timed more like a conventional engine’s for greater power output.
• Bottom line: the 1.5-liter Atkinson-cycle 4-cylinder engine is like having two engines in one.